JP3340569B2 - Aperture control device of light source device for endoscope - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an endoscope in which a movable stop capable of blocking an illumination light path by an arbitrary amount between a light source lamp and a light guide entrance end face of the endoscope is driven by a step motor. The present invention relates to an aperture control device of a light source device for a vehicle.

[0002]

2. Description of the Related Art A movable stop provided between a light source lamp and a light guide entrance end face is driven by a step motor in order to automatically adjust the area of a light beam of illumination light to be incident on a light guide of an endoscope. A known aperture control device is known.

In such an apparatus, a luminance signal indicating the brightness of an endoscopic observation image is repeatedly detected in a short cycle, and a fixed number of drive pulses are given to a step motor every time the luminance signal is detected, thereby making the movable motor movable. The aperture is driven so that the luminance signal value approaches a predetermined value.

When the luminance signal value deviates from the predetermined value, the luminance signal value converges to the predetermined value by repeating the detection and drive control processing several times, and the brightness of the endoscope observation image becomes appropriate. Automatically adjusted to the value.

[0005]

However, if the number of drive pulses given to the step motor for each control process is set to be small, the moving speed of the movable diaphragm becomes slow and the response speed becomes slow. Conversely, if the number of pulses per time is set to be large, the luminance signal value may not converge to a predetermined value and the movable diaphragm may hunt.

Therefore, the number of drive pulses given to the step motor for each control process is set to the most preferable value in consideration of various conditions, but the optimum value is set to the value of the endoscope used. It greatly differs depending on the type, and also greatly differs depending on the usage conditions at each time.

Therefore, conventionally, the response speed of the movable diaphragm is too slow or hunting occurs depending on the conditions, no matter how the number of drive pulses given to the step motor for each control process is set. There was something.

Accordingly, an object of the present invention is to provide an aperture control device of an endoscope light source device which does not cause a response delay or hunting of a movable aperture driven by a step motor even when use conditions change.

[0009]

In order to achieve the above object, an aperture control device for an endoscope light source device according to the present invention comprises an illumination light path between a light source lamp and a light guide entrance end face of the endoscope. An aperture control device of an endoscope light source device in which a movable aperture that can be blocked by an arbitrary amount is driven by a step motor, and repeatedly detects a luminance signal of an endoscope observation image in a short cycle, and each time, In a configuration in which a drive pulse for bringing the luminance signal value close to a predetermined value is applied to the step motor, a plurality of the movable apertures are provided, and the movable apertures are independently driven by the step motor. It is characterized by having done.

The plurality of movable apertures are formed in the same shape, and when the difference between the luminance signal value and the predetermined value is equal to or more than a certain value, the plurality of movable apertures are simultaneously driven by different step motors, When the difference between the luminance signal value and the predetermined value is within a certain range, only one of the plurality of movable diaphragms may be driven.

Alternatively, the change in the amount of light blocking when the stepping motor rotates by one drive pulse is made different for each movable aperture, and which movable aperture is driven corresponds to the difference between the luminance signal value and the predetermined value. May be selected.

It is preferable that the plurality of movable diaphragms have different displacement directions when driven.

[0013]

An embodiment will be described with reference to the drawings. FIG. 1 schematically illustrates the entire configuration of the electronic endoscope 1 and the endoscope light source device 20. The distal end of the insertion section of the endoscope 1 is located at an image forming position of the subject 100 by the objective lens 2, for example. A solid-state imaging device 3 including a charge-coupled device (CCD) is arranged.

An illumination lens 5 for illuminating the subject 100 with a wider light distribution angle of illumination light is disposed facing the exit end of the illumination light guide fiber bundle 4 for illuminating the observation range. ing.

An electrical connector for connecting a signal line for transmitting signals input / output to / from the solid-state imaging device 3 to the light source device 20 is provided at a connector portion of the endoscope 1 which is detachably connected to the light source device 20. 7 and light guide fiber bundle 4
Are arranged.

A light source lamp 22 for generating illumination light to be supplied to the light guide fiber bundle 4 is provided in the light source device 20, and is provided between the incident end of the light guide fiber bundle 4 and the light source lamp 22. Is a condenser lens 24 for converging the illumination light emitted from the light source lamp 22 to the incident end face of the light guide fiber bundle 4.
Is arranged.

Reference numeral 23 denotes a filter that sequentially inserts and removes three color filters of red (R), green (G), and blue (B) into the illumination optical path in order to perform illumination for so-called RGB plane sequential imaging. This is an RGB rotation filter that is driven to rotate at a constant speed.

Two movable diaphragms are provided between the light source lamp 22 and the condenser lens 24 for changing an area of an illumination light beam incident on the light guide fiber bundle 4 by interrupting an illumination light path therebetween by an arbitrary amount. 25, 27 are arranged side by side in the direction of the illumination optical axis.
5 and 27 are independently driven by step motors 26 and 28, respectively.

As shown in FIG. 2, the two movable diaphragms 25 and 27 are formed in the same shape, each of which is formed by bending a thin plate into a U-shape and connecting a rotation axis connected to the center of the bottom surface to an illumination optical axis. And step motors 26 and 28
Is driven to rotate.

Both the movable diaphragms 25 and 27 are shown in FIGS.
As shown in FIG. 7, when the plate surface is parallel to the illumination optical axis, the illumination optical path is not interrupted, and the movable diaphragms 25 and 27 are driven by the step motors 26 and 28 to rotate in correspondence with the rotation. The light path is gradually blocked, so that the illuminating light flux incident on the light guide fiber bundle 4 is reduced.

The rotation axes of the two movable diaphragms 25 and 27 are 90
° They are arranged in different directions. Therefore, when the movable diaphragms 25 and 27 are rotationally driven, the first movable diaphragm 25 blocks the illumination optical path in the vertical direction, for example, and the second movable diaphragm 27
The illumination optical path is blocked in the horizontal direction with little interference with the light blocking range of the first movable stop 25.

The light source device 20 includes a step motor 26,
An aperture control unit 30 for providing a drive pulse to 28 is provided, and a part of a video signal from the solid-state imaging device 3 is input to the aperture control unit 30.

Further, a brightness index for adjusting the brightness of the observation screen in ten steps from "1" to "10" is input from the panel switch 29 on the front of the light source device 20 to the aperture control unit 30. Is done. Then, the brightness index from “1” to “10” is converted by the aperture control unit 30 into, for example, 10-step reference values of 16 to 161.

FIG. 3 is a block diagram showing the contents of the aperture control unit 30. A video signal output from the solid-state image pickup device 3 is input to an integration circuit 9, and one screenful of the signal is integrated for observation. The arithmetic unit 4 generates a luminance signal indicating the brightness of the image.
1 is output.

In the arithmetic section 41, a reference value is input from a panel switch (that is, a reference value setting section) 29, and the reference value and the luminance signal value are compared. And
Based on the result, the forward / reverse determination unit 42 outputs a forward rotation signal for driving the step motors 26 and 28 to close the aperture or a reverse rotation signal for driving the aperture to open the aperture to the motor driving unit 44. Is done.

The motor selector 43 outputs to the motor driver 44 a selection signal indicating whether or not to drive the two step motors 26 and 28, respectively. In response to these signals, the motor drive unit 44 receives the step motors 26 and 28
Of the driving pulse output is controlled.

The arithmetic unit 41, the forward / reverse determining unit 42, the motor selecting unit 43, and the motor driving unit 44 may be constituted by hardware, but may be constituted by a single microcomputer. The function of each unit can be executed by software processing. In that case, the hardware included in the microcomputer is CP
U, RAM and ROM.

FIG. 4 shows movable apertures 25 and 27 using a microcomputer in order to automatically adjust the brightness of an endoscope observation image to always correspond to a set brightness index (that is, a reference value). FIG. 4 is a control flowchart of a first embodiment for controlling the operation of the step motors 26 and 28 for driving.

This control is executed by an interrupt process which is periodically executed at intervals of, for example, 0.03.
When drive pulses are given to the step motors 26 and 28, the number of drive pulses given by one control process is always the same.

In this processing, first, a luminance signal of an endoscope image is input (S1), and if the difference between the reference value and the luminance signal value is not larger than a preset allowable value a, the interruption processing is terminated as it is. (S2).

If the difference between the reference value and the luminance signal value is larger than the allowable value a, the difference between the reference value and the luminance signal value is further compared with a preset selection reference value b (S3). The selection reference value b is a constant larger than the allowable value a. If the difference between the reference value and the luminance signal value is larger than b, the deviation of the luminance signal value with respect to the reference value is large. It is determined that the deviation of the signal value is not large.

If the difference between the reference value and the luminance signal value is larger than b, the first and second stepping motors 26 and 28 are selected as driving targets (S4), and the reference value and the luminance signal value are selected. Is smaller than b, only the second step motor 28 is selected as the drive target (S
5).

If the luminance signal value is larger than the reference value, a forward rotation signal is given as the rotation direction of the step motor to drive the movable aperture in the closing direction (S6, S6).
7) If the luminance signal is not larger than the reference value, a reverse rotation signal is given as the rotation direction of the step motor to drive the movable aperture in the opening direction (S8), and a predetermined fixed number of drive pulses are applied. A signal to be given to the motor is output and the process ends (S9).

As described above, when the deviation of the luminance signal value from the reference value is large, both the first and second stepping motors 26 and 28 are driven, and the illumination brightness is rapidly adjusted. If the deviation of the luminance signal value from the reference value is not large, only the second step motor 28 is driven, so that no hunting occurs.

FIG. 5 shows a movable diaphragm 2 according to a second embodiment of the present invention.
5 and 27 and step motors 26 and 28 are shown, and the length A of the first movable diaphragm 25 is longer than the length B of the second movable diaphragm 27.

As a result, the first and second step motors 2
6 and 28 are rotated by one drive pulse, the first
The change in the light blocking amount of the movable stop 25 is the same as that of the second movable stop 27.
Is larger than the change in the amount of light shielding. Other configurations are the same as those of the first embodiment.

FIG. 6 is a flow chart of the control processing of the second embodiment, which is different from the control processing of S4 of the first embodiment only in that only the first step motor 26 is selected in S14.

In this embodiment, the first movable diaphragm 25 has a large change in the amount of light shielding with respect to the rotation angle.
Only the step motor 26 is selected. Thereby,
As in the first embodiment, when the deviation of the luminance signal value from the reference value is large, the adjustment of the illumination brightness is rapidly performed. If the deviation of the luminance signal value from the reference value is not large, only the second step motor 28 is driven, so that no hunting occurs.

[0039]

According to the present invention, a plurality of movable apertures are provided, and each of the movable apertures is independently driven by a stepping motor. However, if the luminance signal value is largely deviated from the predetermined value, the change in the light shielding amount is performed rapidly, and if the luminance signal value is not largely deviated from the home value, the change in the light shielding amount is slow. Therefore, the response speed can be made as fast as possible without causing hunting of the movable diaphragm.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an overall configuration of a first embodiment.

FIG. 2 is a perspective view of two movable diaphragms according to the first embodiment.

FIG. 3 is a block diagram of an aperture control circuit according to the first embodiment.

FIG. 4 is a flowchart showing the contents of an interrupt process for step motor control according to the first embodiment;

FIG. 5 is a perspective view of two movable diaphragms according to a second embodiment.

FIG. 6 is a flowchart showing the contents of an interrupt process for step motor control according to the second embodiment.

[Explanation of symbols]

 1 Endoscope 25, 27 Movable diaphragm 26, 28 Step motor 40 Microcomputer

Continuation of the front page (56) References JP-A-64-31115 (JP, A) JP-A-62-19614 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) A61B 1 / 00-1/32

Claims (3)

(57) [Claims] A stop control device for an endoscope light source device wherein a movable stop capable of blocking an arbitrary amount of an illumination light path between a light source lamp and a light guide entrance end face of an endoscope is driven by a step motor. And repeatedly detecting a luminance signal of an endoscopic observation image in a short cycle, and each time, a drive pulse for bringing the luminance signal value close to a predetermined value is given to the step motor, Provide a plurality of movable diaphragms and use the same number of movable diaphragms
And the difference between the luminance signal value and the predetermined value is one.
When there is more than a certain limit, the movable diaphragms are independently
Drive with separate step motors, and
When the difference from the predetermined value is within a certain range,
An aperture control device for a light source device for an endoscope, wherein only one of the movable apertures is driven. 2. The change in the amount of light blocking when the stepping motor rotates by one drive pulse is different for each movable aperture, and which movable aperture is driven depends on the difference between the luminance signal value and the predetermined value. The aperture control device for an endoscope light source device according to claim 1, which is selected correspondingly. Wherein said plurality of movable aperture, aperture control device for an endoscope light source device according to claim 1 or 2, wherein the displacement direction is different from each when driven.